Overview
This lecture introduces the human nervous system, outlining its major divisions, core functions, and structural components of both the central and peripheral systems.
Functions of the Nervous System
- Coordinates all activities of the body.
- Enables response and adaptation to internal and external changes.
- Responsible for consciousness and intelligence in humans.
Central Nervous System (CNS)
- Consists of the brain and spinal cord.
- The brain is located within the skull and has six main sections: cerebrum, cerebellum, diencephalon, midbrain, pons, and medulla oblongata.
Brain Sections
- Cerebrum: Largest part, divided into right/left hemispheres and four lobes (frontal—reasoning, parietal—sensory integration, temporal—hearing, occipital—vision).
- Cerebellum: Located at the back of the head; controls muscle coordination, balance, posture, and muscle tone.
- Diencephalon: Contains thalamus (sensory relay) and hypothalamus (regulates autonomic functions, emotions).
- Midbrain: Controls eye and auditory reflexes.
- Pons: Manages reflexes like chewing, tasting, and saliva production.
- Medulla Oblongata: Connects brain and spinal cord; regulates heart, blood vessels, digestion, respiration, and vital reflexes.
Spinal Cord
- Links brain to peripheral nerves throughout the body.
- Divided into four regions: cervical, thoracic, lumbar, and sacral.
- Has afferent (to brain) and efferent (from brain) spinal nerves.
Peripheral Nervous System (PNS)
- Composed of all nerves outside the brain and spinal cord.
- Subdivided into the somatic and autonomic nervous systems.
Somatic Nervous System
- Transmits motor and sensory information to/from CNS.
- Controls voluntary muscle movements and processes sensory input from external stimuli.
Autonomic Nervous System
- Regulates involuntary body functions.
- Subdivided into:
- Sympathetic system: Activates fight or flight response.
- Parasympathetic system: Restores body to normal after danger passes.
Key Terms & Definitions
- Consciousness — the ability of humans to be aware of themselves and their surroundings.
- Central Nervous System (CNS) — brain and spinal cord.
- Peripheral Nervous System (PNS) — all nerves outside the CNS.
- Afferent neurons — carry information toward the CNS.
- Efferent neurons — carry information away from the CNS.
- Somatic Nervous System — controls voluntary movements and sensory information.
- Autonomic Nervous System — manages involuntary body functions.
Action Items / Next Steps
- Review the six main sections of the brain and their functions.
- Study divisions of the spinal cord and role of afferent/efferent nerves.
- Understand the differences between somatic and autonomic systems.